Transcript:

Metallurgy is amazing. So, copper is one of the few metals that can be mined in directly usable form. As a consequence, it was the first metal to be made into an alloy. Copper plus around 12% of tin gives bronze. Copper plus zinc gives brass. Going ahead, iron plus carbon gives steel, and steel plus about 11% of chromium makes it stainless steel. 

It's amazing how metallurgists figured out the additives, and the additives are usually around 11 to 12 percent, and there is a systematic reason why. Let me know in the comments if you understand why 12% of tin is added to copper to make bronze or 11% of chromium is added to steel to make it stainless steel. There's a reason for this. Let me know in the comments if you know.